VOA科学技术2024--NASA Rover Captures Rock Showing Possible Signs of Microbial Life

A Mars explorer operated by the American space agency NASA has captured a rock that scientists say shows possible signs of ancient microbial life.

NASA said in a recent statement that the Perseverance¹ explorer, or rover, collected the rock on July 21. Scientists working on the Perseverance team nicknamed the rock "Cheyava Falls," after the tallest waterfall in the Grand Canyon².

The rover's exploration area is believed to include a former river valley measuring about 400 meters wide. The valley is thought to have formed by water rushing into Jezero Crater³ billions of years ago. Scientists believe the area around Jezero Crater contained large bodies of water in the distant past.

NASA's statement says the rock shows signs of "chemical signatures and structures that could possibly have been formed by life billions of years ago..."

NASA team members based their findings on examinations of the rock with imaging equipment and multiple scientific instruments. But they noted⁴ that additional research is needed to confirm a history of microbial life.

The examinations did suggest the rock contains "organic compounds," NASA said. But the statement added, "While such carbon-based molecules⁵ are considered the building blocks of life, they also can be formed by non-biological processes."

Perseverance uses its robotic arm and drilling equipment to capture rock and soil samples from the Martian surface. So far, it has collected 22 samples. The rover has secured the samples in special containers and they are to be picked up and returned to Earth during a future mission.

Ken⁶ Farley is a project scientist with the Perseverance team at Caltech in Pasadena, California. He said, "Cheyava Falls is the most puzzling, complex, and potentially important rock yet investigated by Perseverance."

Farley said unusual color spots and other structural⁷ elements in the samples suggest "chemical reactions" that might have given energy to ancient microbial life. But he noted that so far, scientists have not been able to identify exactly how the rock formed.

The team described the rock as containing white veins⁹ that may have been created by the substance calcium¹⁰ sulfate. Between the veins, examiners found lines of material with a reddish color. These lines suggest the presence of hematite, a common substance found in many rocks on Earth.

David Flannery is an astrobiologist and member of the Perseverance science team from the Queensland University of Technology in Australia. He said that on Earth, these kinds of rock elements are often linked "with the fossilized record of microbes living in the subsurface."

The scientists said the new findings strengthen existing evidence that such rocks may have been created or were changed by flowing water on Mars billions of years ago.

Caltech's Farley said the rock sample had already been imaged and examined with lasers, X-ray equipment and other instruments as much as possible in recent weeks. He noted that Perseverance has done as much as it can to examine the newly discovered samples.

Farley added, "To fully¹¹ understand what really happened in that Martian river valley at Jezero Crater billions of years ago, we'd want to bring the Cheyava Falls sample back to Earth." That way, he said, "it can be studied with the powerful instruments available in laboratories."

Words in This Story

nickname - n. a name used informally instead of an official name

crater - n. a hole left in the ground by an object that hits it with a huge force

signature - n. a feature in the appearance or qualities of a natural object

drill - v. to make a hole in a hard substance using a special tool

puzzling - adj. difficult to understand or figure out

vein⁸ - n. one of the thin lines found on an object

fossil - n. part of a plant or animal from many years ago that has been preserved in rock

1 perseverance   

n.坚持不懈，不屈不挠

参考例句：

• It may take some perseverance to find the right people.要找到合适的人也许需要有点锲而不舍的精神。
• Perseverance leads to success.有恒心就能胜利。

2 canyon   

n.峡谷，溪谷

参考例句：

• The Grand Canyon in the USA is 1900 metres deep.美国的大峡谷1900米深。
• The canyon is famous for producing echoes.这个峡谷以回声而闻名。

3 crater   

n.火山口，弹坑

参考例句：

• With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
• They came to the lip of a dead crater.他们来到了一个死火山口。

4 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

5 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

6 ken   

n.视野，知识领域

参考例句：

• Such things are beyond my ken.我可不懂这些事。
• Abstract words are beyond the ken of children.抽象的言辞超出小孩所理解的范围.

7 structural   

adj.构造的，组织的，建筑（用）的

参考例句：

• The storm caused no structural damage.风暴没有造成建筑结构方面的破坏。
• The North American continent is made up of three great structural entities.北美大陆是由三个构造单元组成的。

8 vein   

n.血管，静脉；叶脉，纹理；情绪；vt.使成脉络

参考例句：

• The girl is not in the vein for singing today.那女孩今天没有心情唱歌。
• The doctor injects glucose into the patient's vein.医生把葡萄糖注射入病人的静脉。

9 veins   

n.纹理；矿脉( vein的名词复数 )；静脉；叶脉；纹理

参考例句：

• The blood flows from the capillaries back into the veins. 血从毛细血管流回静脉。 来自《简明英汉词典》
• I felt a pleasant glow in all my veins from the wine. 喝过酒后我浑身的血都热烘烘的，感到很舒服。 来自《简明英汉词典》

10 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。

11 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。